Transmitter.



R. S, M. MTHELL,

TRANSMITTER.

APPLIGATION MLED MM 1o, 191s.

l 9@ 9 5 57 u Patented Mar. 17, 1914.

To all wie 'on daga and State of New certain new l0 i transmittens designed for use y ,transmitter f lohectinjsvith sound-recording for both companying di' of the transmitter. F ieg.

ment of anordinary 2 phragm of the 3- the sev the weight ofthe ca lilla" a nu a) i limitate if; attestata Riemann s. iu. mirent.

trovino Haenen co. i

sona.

no., on Vico" appagante 'sied nay te, i

e 'it muy concern Be 1t known that il, Bionaire lill. MiToIiELL, a citizen of the United 'tate l residing at Syracuse, in the county of Onon- York, have invented and useful improvements in Transmitters, of rwhich the following is a specication.

rJllhis invention relates to improvements in in connection with .microp'nonic and telephonie* devices generally, andfthe invention relates/pa" tieularlvto a nhvelnonstructitn ota iway which is adapted andreproducing mach1nes, telephones and the like.

-The object of the. invention is to provide al vibratingdiaphragm in combination with a plurality of opposed electrodes, and a plu'- rality of yvariable and resilient resistants forming parts of the transmitting lines, the said variableresistants forming the electric connections betweenv the .diaphragm and the electrodes, and capable o alternate action increasing and decreasing the resistance in the transmitting lines.

The various features and parts .will be underestood from the detailed description Which follows, and by reference to the acawing, in Which-u f Figure l is a top plan view of my improved transmitter. .l1-Figs?y is a central verI tical cross-section,v teilten on-li'ne 2-2 of Fig. 1, showing the construction and arrangement v 3 is a. horizontal section taken on line 3--3 of Fig. 2. Fig. 4 is a horizontal section taken on line 1 -4l of Fig. 2. Fig. 5 is a cent1-al 1vertici l' seclion; showing 'the construction and arrange- -way transmitte. hat applied thereto. Fig. gmentary section showattaching the spiral reopposite sides of the dia- Way transmitter. Fig. 7 is a diagrammatic view, showing a convenient arrangement ,of the transmitter circuits.

Similar characters of reference are assigned to corresponding parts throughout eral views. H l Heretofore, `3 -Way transmitters have con' ssted of carbon diaphragme which vibrate between two variable electrodes comprising granulated ca'rbon. ln these transmitters, thon and the presente jV ing myflmprovement. 6 is an enlarged. fra ing the method of sis'tance coils to the Specicater. of flletters for use in contell.

Fatented Mar. if?, it@ Serial 3io. l",726. l

oi' the retaining' asbestos ber Aphragnu, of. the transmitter.

The object of'my invention is -uvay trans damp the diato provide mutter, tor use in connection lai' sound reproducin the same c with talking and simig machines, which has arrying capacity as the granulated carbon transmitters, and which has the additional advantage of extreme sensitiveness, in that the resilient carbon'elements disposed between the-opposed electrodes and the diaphragm, oder little or no resistance diaphragm, so that in the atmosphere diete neighborhood of the in sets up a motion in the diaphragm alta-nt fluctuation oi .current due reduction of the. ohrnic resistance in In this 'tvay the ohmic ed and "increased, not g of company between electrodes and the diaph the merest variation of the pressure brought haar upon the surfaces of the spring-s, the diaphragm, and the electrode already in contact. Thus it will be readily seen that With a higher resist-ance in the two resistants springs, the slightest motion of 'the diaphragm Will bring a great" number of convolutions of the springs or. filaments into contact with the electrodes. thus bringing about an enormous range of iuctuation in the circuits o the transmitters.

Referring to Figs. l, 2, 3, l and 6 of the drawing, 2 represents the one-part back of the 3-Way transmitter; which is preferably made of nonconducting material, such as hard rubber, fiber and the like. The hack 2 is nreferably circular in fori and it vided with a concentric bose ci tion 3, 1which is hollow, and in vhicn is disposed an elect-rode comprising ,a solid bloeit str .uncut with a to the e .partin particularlyT adapted ragm, but by nl carbon 4., `which mav be held in `olaceby Y anv suitable means. The body has a'peripheral Bange 5,- tor providing a relatively broad shallow recess, in which is disposed' the diaphragm 7. which in the ipresentl case preferably consists of a relatively thin'disk of carbon. but any; other suitable substance may be used if desired. The diaphragm 7 is prefeiably supported in. the chamber 5 by nenconducting rings 8, which are disposed an the opnosite sides and adjacent the peripheral edge of the diaphragm, as best seen in Fig'. 2. F ie rings 8 preferably consist of lot 11 represents a circular cap, preferably vmade to the same diameter and of the same material as the back 2, which is employed for closing the open side of the back, to

v'which itis secured by means of bolts 9,

which pass through coinciding perforations formed in the back and the cap, as shown. The cap 11 has an embossed or raised portion 12,for providing a cavity 12', in which is disposed a second electrode comprising a block of carbon 13, the latter being solid except for a series of perforations 14, which are grouped around the center of said carbon, and which are employed Jfor carrying the vibrations of sounds to and from the diaphragm chamber 6. The center of the boss'12 of the cap is provided with a relatively large open'ing 15 for `receiving or emitting sounds, and 16 represents an integral horn or mouth-piece, `which is arranged concentric tothe opening 15, and which serves as a receiver and condenser for the v'sc'..md-waves which actuatel the diaphragm The diaphragm 7 of my improved 3-way transmitter connects with the opposed carbon electrodes 4 and 13 by means of two spirall'y wound coils, 17 and 1S, the saidcoils preferably consisting of fiexible and resilient 'carbon wire, although any other high-resistance material may be used for making the coils, and produce good results. The inner end of the coils 17 and 18 connect with the diaphragm, at or near the center thereof, while the outer endsA of the said coils connect to the electrodes 4 and 13, as best seen in Figs. 2 and 6. Various means may be employed for connecting the coils -17 and 18 to the diaphragm 7 but I prefer to make the said connections in the manner shown in Fig. 6, which. consists of perforating the diaphragm, and then inserting a wire tie 2O through the said perforations, the loop of the tie engaging and drawin the end of the coil firmly against when the free ends of the wire are drawn tight and lapped or otherwise arranged, and the wire may then'be held in` the 'ends of place by a drop of solder, as shown at 20. In practice, the diaphragm is spaced only a few thousandths ofian inch from' thecarbon parts 4'and 13, and in order t'o 'allow for the free vibratory movement of the diaphragm in opposite directions, the carbon parts 4 and 13 are provided with coinciding recesses 21, to receive the projecting ends of the ties 20, which bind the coils 17 and-18, as shown in Figs. 2'and 6.,

22 represents'a bon electrode 4, one end of which is suitably connected to the electrode. The 'opposite the face o ,the diaphragm i binding postA for` the car-4 end of the post 22 pas-ses through and extendsb'eyond thecenterof thecasing 2, and

is threaded t'eceive the usual nuts for securing the electric circuit wire 23.

24 represents a second binding post which pierces the casing 2, and its outer end is threaded to receive a pair of nutsv for gripping a wire 25. The inner end of the binding post 24 connects with one end of a metallic conductor 26, the opposite end of said conductor connect-ing with an annular metal ring 27 which is mounted upon the upper side of the diaphragm 7. I v 29 represents a third binding,post,...the inner end of which connects with thecali'ibon electrode 13, the vouter end passing'. through the capv 11, and having threads for receiving nuts which grip a third wire 30. Fig. 5 illustrates av modified form otmy transmitter, in which 2' represents tln back or casing having a hollow raised portion, in which is disposed an electrode, which preferably comprisesa solid block of carbon 4. The back 2 is substantially like 'the corresponding part in the preceding '-iguies, and is arranged to provide a broad recess 6 in which is disposed a diaphragm 7', which is disposed between and supported by rings 8. which may consist of iubbertuhing Vor felt. 12 'represents the cap which closes the open side of the casing, which is provided with an integral4 horn or mouth-piece- 16 which is disposed concentric to the central opening 15,l and through which the sound-waves are carried tothe diaphragm.

17 represents a resilient carbon coil similar to the coils 17 and 18, and which forms the electric connection between the diaphragm and the electrode 4.. The spring 7 may con-A nect with the diaphragm and the electrode in any suitable manner, or as sho-wn in Figs. 2 and 6. The transmitting line or circuit 1 outside of the transmitter proper consists of wires 40 and 41. Wire 40 connects'I with;

,the electrodes 4 by means of a binding post 42, as shown. The wire 41 connects with a binding post 43 which is held in place by a suitable insulating party. 44, which is enibedded in the upper side ofthe electrode 4. The binding post 43 connects with the dia'- phragin 7 by means of a conductor. 45, which in turn connects with a metallic ring 46 which is carried by the dia-phragnn In thia. .iodified form of transmitter, the soundwa e.. entering through the horn 16 vibrate the diaphragm '7' which effects the alternate L y .1,090,557 l a .the preceding wiens, 'feXeep-tingfthat these :partsserre lult-st single trausnifttinp,v A. Je, vQIl'RMSl'lea-Al"oi tn 'hich rendersyth modified 1-delfice peculiar serviceable/tor telephones saudhae me ramsms.

Fig fr' ill'i'strates diagrammatically the arrangement of my 3-Way transmitter in ycon-i.

nection with a receiver, InV F ig. 7" my transmitter' appears disposed between con- 10 cluctors*33 and 34, )vherein the. Wires 23 and 3 0 connect thetransmitter thereto in 'parallel, `While the\u fire leads from the' diaphragm toA ne\sidejoi" aTba-ttery 35, the

opposite side of thebatteryi connects lays* 5 wird with the center of a lineyzf37, .tlie"eplpositie ends of line 37 connecting. with' the corresponding ends of Wires 33 and 34, and

in line 37 .Isnonnect axed resist-ance, as

shown at 38and38.. The opposite end ofthe Wires 33 and 34 connect With theV re-A ceiver The operation oit' my 3Way` transmitter is as follows: lVhen the diaphragm 7 .is V1-A bra'tedl by the sound- Waves coming ,to `itl .35 through the horn 16 and the perforations 14,

the diaphragm alternately ,moves toward and away from thel electrodesfland 13.

`ill/*hen the center of the diaphragm moves eto-4 ward the electrode 4 it compresses the car so loon resistance coilrl toWardsaid-electrode,.

l and forces a greater number of .the convolu` tions of said coil against the face'ofuthe electrod e 4, which lowers the resistance and there-.

by increases the current in the circuit com.

prising the Wires Q3 and 25. At .the same time the kdiaphragm 7 haring moited away` from the electrode v13, tlisengagesa number of' the convolutionsot' the coil 18-irom the face of the electrode 13, which in 'eases thel `40 resistanceandthereby'decreasesth current in the circuit comprising theiwires Qfand 30.

By this arrangement .the Vcurrent Qin either side ofthe diaphragm varies directly asthe pressure ofthe diaphragm, when the dia- 15 phragm Vibrates toward either of the elec; trodes 4 and i3 and the currentthrough either of the said electrodes is' thereby increased in exact ratio to the pressure leX- erted between the diaphragm and the electrodes. The increasing and decreasing of the resistance on the opposite sides of the diaphragm alternately increases and decreases the fluctuations in the electric circuits and Z5-30, andthis increasing and decreasing of theresistancc bythe v1- .brations oi? the. diaphr agm,.induces an alternating current in Wires 33 and 34 and also in the receiver 32. f y

Owing to the spiral arrangement of the :60- coils 17- and 18,`the convolutions of tht said coils never come in contact with each other, the current therefore inusttraverse the coils lengthwise insteadl of taking the shorter 1*- .course by jumping from one convolution tov $6 ,the other. l"Under this arrangementwhen the diaphragm is' vibrated by lhc soundwaves entering the horn lli. the` resistance' on each side of the diaphragm is decreased or increased accordingly as a greater number of the conigelutions are brought into engage'ment with. or disengaged from, ,the face of the electrodes. The carbon coilsV .1T and 18 are preferably of comparatively; une "gage, and therefore have a relativelvv nigh resistance, -Such being the case. a .slgnt ribration of the diaphragm will ciiect a considerable increase or decrease in the resistance of the spirals 17 and 1S by lengthening or shortening 'the portions' ot' the said coils "vhichare fieelfi'om contact with the cle'c- 80 trodes.` v v i By the provisie t. the resistance coils 1T and 18 disposed on .we opposite sides of the diaphragm, and each connecting with a sep- -arate electrode, I am able to produce ai185 extremely sensi-tive transmitter, and at tli'e same time provide wide ranges of'if'ariatious in the opposing resistances, which effect a correspondingli7 wide range of fluctuations in the Velectric circuits.

Having thusY described my invention, what I claim as new and desire to secure'by Letters Patent, is l l. In a B-Way transmitter, 'the combina- `tion with the opposed solid carbon elec--95 .trodes, andfa vibratingdiaphragm interposed between theelectrodes, of a spiral resista-nt interposed between the diaphragm 'and each of said electrodes, said spiral re-v tween the diaphragm and said electrodes' and capable ot'jbeing alternately compressed ahdrelaxed t'or simultaneously decreasin the resistance of one of said resistants, an`

said resistantsfV l 2. Ina S-.Way'transmittely a' pair of op.- t

vposed 'electrodes spaced apart, a support for eaehelectrode, a diaphragm interposed be- Vthe variable resistance elements. y

3. In atl-,way transmitter, the combinaelectrodedisposed on each side of the dia- 'phragm and spaced therefrom, a conductor for each electrode, a separate conductor for the diaphragm, and a pair of resilient spiral -resistants, said resistants opposite' sides of the diaphragm, one end of each resistant connecting with the dia-l A'phragm, the opposite end of each resistant!" Vconi'lecting.with the correspond' fthe-'santas .sistants forming the electric connections bei i for increasingstheQresistanc-e of the other of 7 tween said electrodes, a variable'andre- 110 spiral springs adapted to Vbe tiorr with a diaphragm and a solid' earbon 120 disposed on the' 125 we electrode; i i

the perforated electrode.

neously compressed and relaxed for increasing and decreasing the fluctuations in the transmitting lines formed by said conductors.

et. VIn a S-Way transmitter, the combina' tion with a pair of spaced electrodes and a diaphragm interposed between said electrodes and insulated therefrom, of spiral resist-ants interposed between and connecting the diaphragm with each electrode, each of said resistants forming a part ot' an inde;

ingl solid, the other having a series of perfo.

rations for the passage ot' sound-Waves, of a vibrating diaphragm disposed between said electrodes, apair of sensitive spiral4 springs, said springs disposed on the opposite sides of the diaphragm and coiniect'ingl the diaphragm with the corresponding electrodes, and a horn for carrying the sound-Wavesto `(i. In a S-way transmitter, a pair ofcar bon electrodes, one ofv said electrodes beingv solid, the other electrode having va series of perforatons, saidelectrodes spaced apart and having'independent supports, ay Vibrating diaphragm 'interposed between said elec"- for connectingsaid electrodes for lforming tn'o'sepaiate electric circuits,- wherein said trodes and insulatedthe'refrom, an annular terminal carried by said diaphragm, meansl annnlaiielectrode is common to both of said jcircnits, a variable resilient resistance coil disposed on each side of the diaphragm, one l end of 'each coil connecting :with the diaphragm, the opposite end connecting with the y 'corresponding elect-rode, said coils )adapted to complete the electric circuitsbe= tween said electrodes land the'aiinulanelectrode carried by the-diapliragin,-said coils f capable of being alternately compressed toward said electrodes tordecreasing the resistancein said circuits Whenthe diaphragm is iibrated by sound-waves entering through lthe said perforations, said coilsv capableof being` a'lte'rnatelir relaxed by thevibrating.

of said. diaphragm for increasing the resist'- ance 11i-said circuits.

. In testinioinY whereof I aix'iny signature in presence ot' two Witnesses.

i RICHARD S. M. MITCHELL. Witnesses: v

ROBERT J. CooNEY, Hanni DE WALLACE. 

